JP2003049148A - Adhesive optical film and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive optical film having an adhesive layer for pasting an optical film to a glass substrate of a liquid crystal panel, and free from residue of the adhesive and lack of the adhesive. SOLUTION: This adhesive optical film is obtained by laminating the adhesive layer for pasting the optical film on the glass substrate of the liquid crystal panel on one face of the optical film. The adhesive layer is formed out of an acrylic adhesive, and the adhesive layer is laminated through an anchor layer formed by a polyester-based resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive optical film in which an adhesive layer for adhering the optical film to a glass substrate of a liquid crystal panel is laminated on one surface of the optical film. Furthermore, the present invention relates to a liquid crystal display device using the adhesive optical film. Examples of the optical film include a polarizing film or a film obtained by laminating a retardation film, an optical compensation film, a brightness enhancement film, an antiglare sheet and the like on the polarizing film.

[0002]

2. Description of the Related Art In a liquid crystal display, it is essential to dispose polarizing elements on both sides of a glass substrate forming the outermost surface of the liquid crystal panel because of its image forming system. It is attached to the surface. In addition to the polarizing film on the outermost surface of the liquid crystal panel,
Various optical elements have been used to improve the display quality of a display. For example, a retardation film for preventing coloration, a viewing angle widening film for improving the viewing angle of a liquid crystal display, and a brightness enhancement film for enhancing the contrast of the display are used. These films are collectively called optical films.

When the optical film is attached to the outermost surface of a liquid crystal panel, an adhesive is usually used. In addition, since the optical film can be instantly fixed to the outermost surface of the liquid crystal panel and has the merit of not requiring a drying step to fix the optical film, the pressure-sensitive adhesive is preliminarily attached to one side of the optical film. It is provided as a layer. That is, an adhesive optical film is generally used to attach the optical film to the outermost surface of the liquid crystal panel.

The necessary properties required for the pressure-sensitive adhesive are as follows: (1) When the optical film is attached to the outermost surface of the liquid crystal panel, the attachment position is incorrect, or foreign matter is caught in the attachment surface. In addition, the optical film can be peeled from the outermost surface of the liquid crystal panel and re-bonded (rework), (2) it has stress relaxation property to prevent optical unevenness caused by dimensional change of the optical film,
(3) There is no problem caused by the pressure-sensitive adhesive in a durability test such as heating and humidification that is usually performed as an environmental promotion test.

With respect to the reworkability of (1) above, in particular, in conventional adhesive optical films, the adhesiveness between the adhesive layer and the optical film substrate is low, so the adhesive optical film is peeled from the liquid crystal panel. At that time, there was a problem that a part of the pressure-sensitive adhesive of the pressure-sensitive adhesive optical film remained on the surface of the liquid crystal panel (hereinafter referred to as the pressure-sensitive adhesive remaining).

In addition, recently, the display frame using a liquid crystal panel has become narrower, and the display quality may be remarkably deteriorated due to the defect occurring at the edge of the liquid crystal panel. The defect at the edge of the optical film is also a problem. Came to be. There are various defects at the end of the optical film, but the most common one is a defect that the adhesive is chipped at the end (hereinafter referred to as adhesive deficiency). This occurs when the optical film is handled, the edge of the optical film hits something, and a part of the pressure-sensitive adhesive layer is chipped. Many of these problems have occurred in conventional adhesive optical films.

[0007]

DISCLOSURE OF THE INVENTION The present invention is a pressure-sensitive adhesive type optical film provided with a pressure-sensitive adhesive layer for bonding an optical film to a glass substrate of a liquid crystal panel. An object is to provide a non-adhesive optical film. Furthermore, it aims at providing the liquid crystal display device using the said adhesive type optical film.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and found that the adhesive optical film described below can achieve the above object, and completed the present invention.

That is, the present invention is a pressure-sensitive adhesive type optical film in which a pressure-sensitive adhesive layer for bonding the optical film to a glass substrate of a liquid crystal panel is laminated on one surface of the optical film, wherein the pressure-sensitive adhesive layer is A pressure-sensitive adhesive optical film, which is formed of an acrylic pressure-sensitive adhesive, and the pressure-sensitive adhesive layer is laminated via an anchor layer formed of a polyester-based resin.

In the pressure-sensitive adhesive optical film of the present invention described above, it is considered that the main cause of the occurrence of pressure-sensitive adhesive residue and chipping of the pressure-sensitive adhesive is the low adhesion between the pressure-sensitive adhesive layer and the optical film substrate, and the pressure-sensitive adhesive layer and the optical film substrate. By interposing an anchor layer formed of a polyester resin between the materials, the adhesion between the pressure-sensitive adhesive layer and the optical film is improved. Thereby, even when the adhesive optical film is peeled off from the liquid crystal panel, the adhesive remaining on the liquid crystal panel of the adhesive laminated on the optical film can be prevented. In addition, it is possible to greatly reduce the pressure-sensitive adhesive chipping in which a part of the pressure-sensitive adhesive falls off at the end of the film when handling the pressure-sensitive adhesive optical film.

An example in which an ethyleneimine adduct of polyacrylic acid ester is provided as an anchor layer between the pressure-sensitive adhesive layer and the optical film substrate is known (Japanese Patent Laid-Open Publication No. H10 (1998) -109242).
-201818). However, it cannot be said that such an anchor layer can sufficiently improve the adhesion between the pressure-sensitive adhesive layer and the optical film substrate.

In the pressure-sensitive adhesive optical film, it is preferable that the polyester resin forming the anchor layer has polyester as a main skeleton and has a side chain having a hydroxyl group. The polyester resin forming the anchor layer is not particularly limited, but those having a hydroxyl group are preferable because the adhesiveness between the pressure-sensitive adhesive layer and the optical film is good.

In the pressure-sensitive adhesive optical film, it is preferable that the acrylic pressure-sensitive adhesive forming the pressure-sensitive adhesive layer contains as a base polymer an acrylic polymer containing a monomer having an N element as a monomer unit. The acrylic polymer, which is the base polymer of the acrylic pressure-sensitive adhesive, is not particularly limited, but the one containing a monomer having an N element, preferably a monomer having a functional group containing an N element as a monomer unit is an adhesive layer and a polyester resin. It is preferable because the adhesion to the layer is improved.

In the pressure-sensitive adhesive optical film, the acrylic pressure-sensitive adhesive forming the pressure-sensitive adhesive layer preferably contains an isocyanate-based polyfunctional compound. A polyfunctional compound can be blended with the acrylic pressure-sensitive adhesive, but among the polyfunctional compounds, the incyanate-type polyfunctional compound reacts with the hydroxyl groups present in the polyester resin layer and the hydroxyl groups present in the protective layer to produce adhesive properties. It can improve the adhesion between the agent layer and the polyester resin layer, and is present in triacetyl cellulose, diacetyl cellulose, monoacetyl cellulose, etc. used as a protective layer on the outermost surface of the optical film (polarizing film) through the polyester resin layer. It is preferable since it can react with the hydroxyl group of the polyester resin layer and the adhesion between the polyester resin layer and the optical film (protective layer of the polarizing film) is improved.

In the pressure-sensitive adhesive optical film, the pressure-sensitive adhesive layer surface of the pressure-sensitive adhesive optical film and the vapor deposition surface of the vapor deposition film obtained by vapor-depositing indium-tin oxide on the polyethylene terephthalate film are bonded together, and then the polyethylene terephthalate film is formed. When peeled at a speed of 300 mm / min in the 180 ° direction, the stress at 25 ° C is 13 N / 25.
It is preferably at least mm.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive type optical film and the vapor-deposited surface of the above-mentioned vapor-deposited film have a strong adhesive force, and if they are peeled after being bonded, they are peeled off by the polyester resin layer of the anchor layer. The stress is preferably 13 N / 25 mm or more, more preferably 16 N / 25 mm or more.

Further, the present invention relates to a liquid crystal display device using the adhesive optical film. The pressure-sensitive adhesive optical film of the present invention, according to various usage aspects of the liquid crystal display device,
It is used by being attached to the outermost glass substrate of a liquid crystal panel.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The acrylic pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive optical film of the present invention has an acrylic polymer having an alkyl (meth) acrylate monomer unit as a main skeleton as a base polymer. In addition, (meth) acrylate refers to acrylate and / or methacrylate, and has the same meaning as (meth) of the present invention. The average carbon number of the alkyl group of the alkyl (meth) acrylate constituting the main skeleton of the acrylic polymer is 1 to
It is about 12 and specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. They can be used alone or in combination. Among these, alkyl (meth) acrylates having an alkyl group having 1 to 7 carbon atoms are preferable.

A monomer unit having a carboxyl group, a monomer unit having a hydroxyl group, a monomer unit containing an N element, and the like can be introduced into the acrylic polymer. Of these, a monomer unit containing an N element as a monomer is preferable. Examples of the monomer having a carboxyl group include acrylic acid, methacrylic acid, fumaric acid, maleic acid and itaconic acid. Examples of the monomer having a hydroxyl group include a hydroxyl group-containing monomer such as 2-hydroxyethyl (meth) acrylate and N-methylol (meth) acrylamide, hydroxybutyl (meth) acrylate and hydroxyhexyl (meth) acrylate. As the N element-containing monomer,
(Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, (meth) acryloylmorpholine, (meth) acetonitrile, vinylpyrrolidone, N-cyclohexylmaleimide, itaconimide, N, N- Examples thereof include dimethylaminoethyl (meth) acrylamide. In addition, as the acrylic polymer, a monomer having a functional group such as an epoxy group-containing monomer such as glycidyl (meth) acrylate, vinyl acetate, styrene or the like can be used as long as the performance of the pressure-sensitive adhesive is not impaired. . These monomers can be used alone or in combination of two or more.

Alkyl (meth) in acrylic polymer
The ratio of the monomer unit (a) other than acrylate is
Monomer Although not particularly limited, the weight ratio (a / A) of the monomer unit (A) (excluding the monomer unit (a)) constituting the acrylic polymer is 0.0
It is preferably about 01 to 0.12, and more preferably 0.005 to 0.1.

The average molecular weight of the acrylic polymer is not particularly limited, but the weight average molecular weight is preferably about 300,000 to 2,500,000.

The acrylic polymer can be produced by various known methods, for example, a radical polymerization method such as a bulk polymerization method, a solution polymerization method or a suspension polymerization method can be appropriately selected. As the radical polymerization initiator, various known ones such as azo type and peroxide type can be used, and the reaction temperature is usually 50 to
The reaction time is about 85 ° C and the reaction time is about 1 to 8 hours. Among the above-mentioned production methods, the solution polymerization method is preferable, and a polar solvent such as ethyl acetate or toluene is generally used as the solvent for the acrylic polymer. Solution concentration is usually 20 ~
It is set to about 80% by weight.

Examples of the polyfunctional compound that can be blended with the acrylic pressure-sensitive adhesive include organic crosslinking agents and polyfunctional metal chelates. Examples of the organic crosslinking agent include epoxy crosslinking agents, isocyanate crosslinking agents, imine crosslinking agents and the like. As the organic crosslinking agent, an isocyanate crosslinking agent is preferable. The polyfunctional metal chelate is one in which a polyvalent metal is covalently or coordinately bonded to an organic compound. As the polyvalent metal atom, Al, Cr, Zr, Co,
Cu, Fe, Ni, V, Zn, In, Ca, Mg, M
Examples include n, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Among these, Al, Zr and Ti are preferable. Further, the atom in the organic compound which forms a covalent bond or a coordinate bond includes an oxygen atom and the like, and the organic compound includes an alkyl ester, an alcohol compound, a carboxylic acid compound, an ether compound and a ketone compound.

The mixing ratio of the acrylic polymer and the polyfunctional compound is not particularly limited, but usually 0.01 to 6 parts by weight of the polyfunctional compound (solid content) to 100 parts by weight of the acrylic polymer (solid content). Part, preferably 0.1
It is about 3 parts by weight.

Further, the pressure-sensitive adhesive composition may contain a filler, a pigment, a colorant, etc., which may be a tackifier, a plasticizer, glass fibers, glass beads, metal powder, other inorganic powder, etc., if necessary. Fillers, antioxidants, ultraviolet absorbers, silane coupling agents, and the like, and various additives may be appropriately used within a range not departing from the object of the present invention. Further, it may be a pressure-sensitive adhesive layer containing fine particles and exhibiting light diffusion property.

As the polyester resin forming the anchor layer, those obtained from a dicarboxylic acid component and a glycol component as a main skeleton, and those capable of forming a coating film can be used without particular limitation. Either a water dispersion type or a water dissolution type may be used. The weight average molecular weight of Maya is not particularly limited, but is about 5,000 to 50,000.

As the dicarboxylic acid component, terephthalic acid, isophthalic acid, orthophthalic acid, naphthalene dicarboxylic acid, biphenyl dicarboxylic acid, 5-sodium sulfoisophthalic acid and other aromatic dicarboxylic acids; succinic acid, adipic acid, azelaic acid, sebacic acid, Aliphatic dicarboxylic acids such as dodecanedioic acid and dimer acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid and their acid anhydrides. To be

On the other hand, as the glycol component, ethylene glycol, 1,2-propylene glycol, 1,3-
Propanediol, 1,4-butanediol, 1,5-
Aliphatic glycols such as petanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butylpropanediol; 1,4 An alicyclic glycol such as cyclohexanedimethanol; glycols obtained by adding ethylene oxide or propylene oxide to two phenolic hydroxyl groups of diethylene glycol, triethylene glycol, dipropylene glycol and bisphenol, polyethylene glycol, Examples thereof include ether bond-containing glycols such as polypropylene glycol and polytetramethylene glycol.

Further, a trifunctional or higher functional polycarboxylic acid and / or polyol can be copolymerized in the polyester resin. Examples of trifunctional or higher polycarboxylic acids include (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid,
(Anhydrous) benzophenone tetracarboxylic acid, trimesic acid, ethylene glycol bis (anhydro trimellitate), glycerol tris (anhydro trimellitate) and the like. Examples of trifunctional or higher functional polyols include glycerin, trimethylolethane, trimethylolpropane and pentaerythritol.

The polyester resin may have the above-mentioned polyester as a main skeleton and a side chain may be introduced therein.
Those having a functional group such as a hydroxyl group can be introduced into the side chain. Examples of the method include a method in which a dicarboxylic acid containing a polymerizable unsaturated double bond is used as the dicarboxylic acid component, and a radically polymerizable monomer is graft-polymerized thereto.

Examples of the dicarboxylic acid containing a polymerizable unsaturated double bond include α, β-unsaturated dicarboxylic acids such as fumaric acid, maleic acid, maleic anhydride, itaconic acid,
Examples of citraconic acid and alicyclic dicarboxylic acid containing an unsaturated double bond include 2,5-norbornene dicarboxylic acid anhydride and tetrahydrophthalic anhydride.

The radical-polymerizable monomer to be graft-polymerized on the polyester resin is not particularly limited, and when a functional group is introduced into the side chain, a radical-polymerizable monomer having a functional group is appropriately used. It is selected and used. Examples of the functional group include a hydroxyl group, a carboxyl group, a phosphoric acid group, a phosphorous acid group, a sulfonic acid group, an amide group, a quaternary ammonium salt, an acid anhydride group, a glycidyl group, and a chloro group. Of these, it is preferable to use one having a hydroxyl group. Examples of the radically polymerizable monomer having a hydroxyl group include the above-exemplified hydroxyl group-containing acrylic monomers. The radical-polymerizable monomer is not limited to the above-mentioned monomer having a functional group, and an alkyl (meth) acrylic acid ester or the like can be copolymerized.
The ratio between the polyester main chain and the side chain is not particularly limited, but the main chain / side chain has a weight ratio of 40/60 to 95.
It is preferably in the range of / 5.

As shown in FIG. 1, the pressure-sensitive adhesive optical film of the present invention has an anchor layer 2 in which a pressure-sensitive adhesive layer 3 for sticking to a glass substrate of a liquid crystal panel is a polyester resin layer on the optical film 1. It is provided through. Also,
A release sheet 4 can be provided on the adhesive layer 3.

As the optical film 1, one used for forming a liquid crystal display device or the like is used, and the kind thereof is not particularly limited. For example, the optical film may be a polarizing film. A polarizing film having a transparent protective film on one side or both sides of a polarizer is generally used.

The polarizer is not particularly limited and various kinds can be used. Examples of the polarizer include a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, and an ethylene / vinyl acetate copolymer partially saponified film, and a dichroic dye such as iodine or a dichroic dye. Examples include polyene oriented films, such as those obtained by adsorbing a volatile substance and uniaxially stretched, polyvinyl alcohol dehydration products, polyvinyl chloride dehydrochlorination products, and the like. Among these, a polarizer made of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching is produced by, for example, immersing polyvinyl alcohol in an aqueous solution of iodine, dyeing it, and stretching it to 3 to 7 times its original length. You can If necessary, it can be immersed in an aqueous solution of potassium iodide, which may contain boric acid, zinc sulfate, zinc chloride or the like. If necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, it is possible to wash the stains and anti-blocking agents on the surface of the polyvinyl alcohol-based film, and by swelling the polyvinyl alcohol-based film, the effect of preventing unevenness such as uneven dyeing is also obtained. is there. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching and then dyeing with iodine. It can be stretched in an aqueous solution of boric acid or potassium iodide, or in a water bath.

As a material for forming the transparent protective film provided on one side or both sides of the above-mentioned polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like is preferable. For example, polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose, acrylic-based polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile-styrene copolymer (AS resin). Examples thereof include a polymer and a polycarbonate polymer.
Further, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymer, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers. , Polyethersulfone polymer, polyetheretherketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer,
An arylate-based polymer, polyoxymethylene-based polymer, epoxy-based polymer, a blend of the above polymers, and the like are also examples of the polymer forming the transparent protective film. The transparent protective film can also be formed as a cured layer of an acrylic, urethane-based, acrylic urethane-based, epoxy-based, silicone-based, etc. thermosetting or ultraviolet curable resin. Of these, cellulosic polymers are preferred. The thickness of the transparent protective film is not particularly limited, but is generally 500 μm or less,
1 to 300 μm is preferable. In particular, the thickness is preferably 5 to 200 μm.

The surface of the transparent protective film on which the polarizer is not adhered (the surface on which the coating layer is not provided) is subjected to a treatment for the purpose of hard coat layer, antireflection treatment, sticking prevention, diffusion or antiglare. May be

The hard coat treatment is carried out for the purpose of preventing scratches on the surface of the polarizing plate. For example, a hardened film excellent in hardness and sliding characteristics made of an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the transparent protective film.
The antireflection treatment is carried out for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to conventional methods. Further, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer.

The anti-glare treatment is carried out for the purpose of preventing external light from being reflected on the surface of the polarizing plate and obstructing the visual recognition of the light transmitted through the polarizing plate. For example, a sand blasting method or an embossing method is used. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a surface-rendering method or a method of blending transparent fine particles. The fine particles to be contained in the formation of the surface fine uneven structure are, for example, conductive particles made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles and organic fine particles made of a crosslinked or uncrosslinked polymer are used. When forming the surface fine uneven structure, the amount of the fine particles used is generally about 2 to 50 parts by weight based on 100 parts by weight of the transparent resin forming the surface fine uneven structure.
25 parts by weight is preferred. The anti-glare layer may also serve as a diffusion layer (such as a viewing angle enlarging function) for diffusing the light transmitted through the polarizing plate and enlarging the viewing angle.

The antireflection layer, the antisticking layer, the diffusion layer, the antiglare layer and the like can be provided on the transparent protective film itself, or as an optical layer separately from the transparent protective film. it can.

An isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex adhesive, an aqueous polyester or the like is used for the adhesion treatment between the polarizer and the transparent protective film.

The optical film of the present invention comprises:
In practical use, other optical layers can be laminated and used. Although the optical layer is not particularly limited, for example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including a wavelength plate such as 1/2 or 1/4), and a viewing angle compensation film. One or two or more optical layers that may be used can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a reflecting plate or a semi-transmissive reflecting plate is further laminated on a polarizing plate, an elliptically polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on a polarizing plate, a polarizing plate A wide viewing angle polarizing plate in which a viewing angle compensation film is further laminated on the plate, or a polarizing plate in which a brightness improving film is further laminated on the polarizing plate is preferable.

The reflective polarizing plate is a polarizing plate provided with a reflective layer, and is for forming a liquid crystal display device of the type that reflects incident light from the viewing side (display side) to display. Further, there is an advantage that it is possible to omit the incorporation of a light source such as a backlight and to easily reduce the thickness of the liquid crystal display device. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like, if necessary.

Specific examples of the reflective polarizing plate include a transparent protective film which is mat-treated if necessary, and a foil or a vapor deposition film made of a reflective metal such as aluminum is attached to one surface to form a reflective layer. can give. Further, by incorporating fine particles into the transparent protective film to form a surface fine uneven structure,
There is also one having a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has the advantage that diffused incident light is diffused to prevent directivity and glare, and uneven brightness can be suppressed. Further, the transparent protective film containing fine particles also has an advantage that incident light and reflected light thereof are diffused when they pass therethrough to further suppress uneven brightness. The reflective layer having a fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective film is formed by, for example, a vacuum deposition method, an ion plating method,
It can be performed by a method of directly attaching a metal to the surface of the transparent protective layer by an appropriate method such as a vapor deposition method such as a sputtering method or a plating method.

The reflection plate may be used as a reflection sheet in which a reflection layer is provided on an appropriate film according to the transparent film, instead of the method of directly applying to the transparent protective film of the polarizing plate. Since the reflective layer is usually made of a metal, the use form in which the reflective surface is covered with a transparent protective film, a polarizing plate, or the like prevents the reduction of the reflectance due to oxidation, and thus the long-lasting initial reflectance. It is more preferable from the viewpoint of avoiding the additional provision of the protective layer.

The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror which reflects and transmits light in the reflective layer. The semi-transmissive polarizing plate is usually provided on the back side of the liquid crystal cell, and when the liquid crystal display device is used in a relatively bright atmosphere,
An image is displayed by reflecting incident light from the viewing side (display side), and in a relatively dark atmosphere, an image is displayed using a built-in light source such as a backlight built into the back side of the semi-transmissive polarizing plate. It is possible to form a liquid crystal display device of the type that displays That is, the semi-transmissive polarizing plate can save energy for using a light source such as a backlight in a bright atmosphere, and is useful for forming a liquid crystal display device of a type that can be used with a built-in light source even in a relatively bright atmosphere. Is.

An elliptical polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on the polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called ¼ wavelength plate (also called a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also called a λ / 2 plate) is usually used to change the polarization direction of linearly polarized light.

The elliptically polarizing plate compensates (prevents) coloring (blue or yellow) generated by the birefringence of the liquid crystal layer of a spurts twisted nematic (STN) type liquid crystal display device, and is used for black and white display without the coloring. Used effectively. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can also compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed obliquely. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has a function of preventing reflection.

Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. Although the thickness of the retardation plate is not particularly limited, it is generally about 20 to 150 μm.

Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate and poly. Ether sulfone, polyphenylene sulfide, polyphenylene oxide,
Examples thereof include polyallyl sulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulosic polymers, and various binary and ternary copolymers, graft copolymers, blends thereof, and the like. These polymer materials become oriented materials (stretched film) by stretching.

Examples of the liquid crystalline polymer include various types of main chain type and side chain type in which a conjugated linear atomic group (mesogen) for imparting liquid crystal orientation is introduced into the main chain or side chain of the polymer. And so on. Specific examples of the main chain type liquid crystalline polymer include a structure in which a mesogenic group is bonded by a spacer portion that imparts flexibility, such as a nematic oriented polyester liquid crystalline polymer, a discotic polymer or a cholesteric polymer. . Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin is provided through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. These liquid crystalline polymers are prepared by, for example, rubbing the surface of a thin film of polyimide or polyvinyl alcohol formed on a glass plate, or obliquely vapor-depositing silicon oxide to form a solution of the liquid crystalline polymer on the treated surface. It is performed by developing and heat treating.

The retardation plate may be one having an appropriate retardation according to the purpose of use, such as various wavelength plates or one for the purpose of compensating for the viewing angle and the like due to birefringence of the liquid crystal layer. It may be one in which at least one type of retardation plate is laminated to control optical characteristics such as retardation.

The elliptically polarizing plate and the reflection type elliptically polarizing plate are obtained by laminating the polarizing plate or the reflection type polarizing plate and the retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can be formed by sequentially stacking them separately in the manufacturing process of a liquid crystal display device so as to form a combination of a (reflection type) polarizing plate and a retardation plate. An optical film such as a polarizing plate is excellent in stability of quality, workability of lamination, and the like, and has an advantage that manufacturing efficiency of a liquid crystal display device can be improved.

The viewing angle compensation film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction, not perpendicular to the screen. Such a viewing angle compensating retardation plate includes, for example, a retardation film, an orientation film of a liquid crystal polymer or the like, or a transparent substrate on which an orientation layer of a liquid crystal polymer or the like is supported. The ordinary retardation film is a birefringent polymer film uniaxially stretched in the plane direction, whereas the retardation plate used as the viewing angle compensation film is biaxially stretched in the plane direction. A polymer film having birefringence, or a bidirectionally stretched film such as a polymer or a tilt-oriented film having a birefringence in which the refractive index in the thickness direction stretched uniaxially in the plane direction and also stretched in the thickness direction is controlled. Used. Examples of the tilted oriented film include those obtained by adhering a heat-shrinkable film to a polymer film and subjecting the polymer film to stretching treatment and / or shrinking treatment under the action of the shrinkage force caused by heating, and those obtained by obliquely orienting a liquid crystal polymer. Can be mentioned. The raw material polymer of the retardation plate is the same as the polymer explained in the previous retardation plate, which prevents coloration due to the change of the viewing angle due to the phase difference due to the liquid crystal cell and enlarges the viewing angle for good viewing. An appropriate one can be used for the purpose such as.

From the standpoint of achieving a wide viewing angle with good visibility, an optically anisotropic layer composed of a liquid crystal polymer alignment layer, particularly a discotic liquid crystal polymer tilted alignment layer, was supported by a triacetyl cellulose film. An optical compensation retardation plate can be preferably used.

A polarizing plate in which a polarizing plate and a brightness enhancement film are bonded together is usually used by being provided on the back side of a liquid crystal cell. The brightness enhancement film has a property of reflecting linearly polarized light of a predetermined polarization axis or circularly polarized light of a predetermined direction when natural light is incident due to reflection from a backlight of a liquid crystal display device or the back side, and transmits other light. A polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter and obtain transmitted light in a predetermined polarization state, and light other than the predetermined polarization state is reflected without being transmitted. It The light reflected by the surface of the brightness enhancement film is inverted through a reflection layer or the like provided on the rear side of the brightness enhancement film to be re-incident on the brightness enhancement film, and part or all of the light is transmitted as light in a predetermined polarization state to achieve brightness. The brightness can be improved by increasing the amount of light transmitted through the improvement film and by supplying polarized light that is difficult to be absorbed by the polarizer to increase the amount of light that can be used for liquid crystal display image display and the like. That is,
When light is input from the back side of the liquid crystal cell through a polarizer without using a brightness enhancement film, almost all light with a polarization direction that does not match the polarization axis of the polarizer is reflected by the polarizer. It is absorbed and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, about 50% of light is absorbed by the polarizer, and the amount of light that can be used for displaying the liquid crystal image is reduced accordingly, and the image becomes dark. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and then inverted through a reflection layer or the like provided behind it. The light-increasing film transmits only the polarized light whose polarization direction is such that the light reflected and inverted between the two can pass through the polarizer. Since the light is supplied to the polarizer, light from a backlight or the like can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

As the above-mentioned brightness enhancement film, for example, a multilayer thin film of a dielectric or a multilayer laminate of thin films having different refractive index anisotropies is transmitted and linearly polarized light of a predetermined polarization axis is transmitted while other light is reflected. Those that exhibit the characteristics of, such as an oriented film of a cholesteric liquid crystal polymer or an oriented liquid crystal layer supported on a film substrate, reflect either left-handed or right-handed circularly polarized light and transmit other light. Appropriate materials such as those exhibiting characteristics can be used.

Therefore, in the brightness enhancement film of the type which transmits the linearly polarized light having the predetermined polarization axis, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby suppressing the absorption loss by the polarizing plate. It can be efficiently transmitted. On the other hand, in the case of a type of brightness enhancement film that drops circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on the polarizer, but from the viewpoint of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable that the light is incident on the polarizing plate. By using a ¼ wavelength plate as the retardation plate, circularly polarized light can be converted into linearly polarized light.

The retardation plate functioning as a quarter-wave plate in a wide wavelength range such as a visible light region is, for example, a retardation layer functioning as a quarter-wave plate and another retardation film for light-color light having a wavelength of 550 nm. It can be obtained by a method of superposing a retardation layer exhibiting characteristics, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one layer or two or more retardation layers.

As for the cholesteric liquid crystal layer,
Two layers or three layers with different reflection wavelengths
By arranging the layers so as to overlap each other, it is possible to obtain an element that reflects circularly polarized light in a wide wavelength range such as a visible light region, and based on that, it is possible to obtain transmitted circularly polarized light in a wide wavelength range.

Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers, like the above-mentioned polarization separation type polarizing plate. Therefore, it may be a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above reflective polarizing plate or semi-transmissive polarizing plate is combined with a retardation plate.

The optical film in which the optical layer is laminated on the polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. Has an advantage that it is excellent in quality stability and assembling work and can improve the manufacturing process of a liquid crystal display device or the like. Appropriate adhesion means such as an adhesive layer may be used for lamination. When the above-mentioned polarizing plate and other optical layers are adhered, their optical axes can be arranged at appropriate angles depending on the intended retardation characteristics and the like.

The method of forming the anchor layer 2 made of a polyester resin layer on the above-mentioned optical film 1 is not particularly limited, and for example, a method of applying a solution or dispersion of a polyester resin to the optical film 1 and drying it. Etc. The thickness of the anchor layer 2 (dry film thickness) is not particularly limited, but is preferably about 0.01 to 2 μm.

The pressure-sensitive adhesive layer 3 is formed by laminating it on the anchor layer 2. The forming method is not particularly limited, and examples thereof include a method in which the pressure-sensitive adhesive composition (solution) is applied to the anchor layer 2 and dried, and a method in which the release sheet 4 provided with the pressure-sensitive adhesive layer 3 is used for transfer. The pressure-sensitive adhesive layer 3 (dry film thickness) is not particularly limited in thickness, but is preferably about 10 to 40 μm.

As the constituent material of the release sheet 4,
Paper, synthetic resin film such as polyethylene, polypropylene, polyethylene terephthalate, rubber sheet, paper,
Appropriate thin sheets such as cloth, non-woven fabric, net, foamed sheet, metal foil, and laminates thereof can be used. In order to enhance the releasability from the pressure-sensitive adhesive layer 2, the surface of the release sheet 3 may be treated with silicone, long-chain alkyl, or
It may be subjected to a peeling treatment such as a fluorine treatment.

In each layer such as the optical film and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive optical film of the present invention, for example, salicylate compound, benzophenol compound, benzotriazole compound, cyanoacrylate compound, nickel complex salt compound, etc. It may be one having an ultraviolet absorbing ability by a method such as a method of treating with the ultraviolet absorbent of 1.

The pressure-sensitive adhesive optical film of the present invention can be preferably used for forming various devices such as liquid crystal display devices. The liquid crystal display device can be formed in a conventional manner. That is, a liquid crystal display device is generally formed by appropriately setting components such as a liquid crystal cell, an adhesive optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no particular limitation except that the polarizing plate or the optical film according to the invention is used, and the conventional method can be applied. Also for liquid crystal cells, for example, TN type or ST
Any type such as N type and π type may be used.

It is possible to form an appropriate liquid crystal display device such as a liquid crystal display device in which an adhesive optical film is arranged on one side or both sides of a liquid crystal cell or a liquid crystal display device using a backlight or a reflector in an illumination system. In that case, the polarizing plate or the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When a polarizing plate or an optical film is provided on both sides, they may be the same or different. Further, when forming the liquid crystal display device, for example, a diffusion plate, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, a backlight, and other appropriate components are provided at appropriate positions in a single layer or Two or more layers can be arranged.

[0070]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In addition, in each example, a part is a weight part.

Example 1 (Preparation of adhesive) 88 parts of butyl acrylate, 3 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate,
0.3 part of azobisisobutyronitrile and 250 parts of ethyl acetate were stirred and reacted at about 60 ° C. for 6 hours to obtain an acrylic polymer solution having a weight average molecular weight of 1,650,000. To the acrylic polymer solution, 0.5 parts of Polyurethane Co., Ltd. Coronate L, which is an isocyanate-based polyfunctional compound, was added to 100 parts of the polymer solid content,
An adhesive solution was prepared.

(Preparation of adhesive optical film) Thickness 80 μ
The polyvinyl alcohol film of m was stretched 5 times in an aqueous iodine solution and then dried, and a triacetyl cellulose film was adhered to both sides via an adhesive to obtain a polarizing film. Water-dispersible polyester resin Vylonal MD- manufactured by Toyobo Co., Ltd. is used on the surface of this polarizing film.
1400 was applied so that the thickness after drying would be 0.1 μm,
It dried and the polarizing film with an anchor layer was obtained. The pressure-sensitive adhesive solution prepared as described above was applied onto a release paper having a thickness of 35 μm so that the thickness after drying would be 18 μm, and this was laminated on the anchor layer surface of the polarizing film with an anchor layer prepared as described above for adhesion. A type polarizing film was obtained.

Example 2 (Preparation of pressure-sensitive adhesive) 92 parts of butyl acrylate, 8 parts of acrylamide, 0.3 part of azobisisobutyronitrile and 250 parts of ethyl acetate were reacted with stirring at about 60 ° C. for 6 hours, An acrylic polymer solution having a weight average molecular weight of 1,500,000 was obtained. An isocyanate polyfunctional compound, Coronate L manufactured by Nippon Polyurethane Company, was added to the acrylic polymer solution in an amount of 0.
An adhesive solution was prepared by adding 2 parts.

(Production of Adhesive Optical Film) An adhesive polarizing film was produced in the same manner as in Example 1 except that an anchor layer-attached polarizing film was produced in the same manner as in Example 1 and the above adhesive solution was used. Was produced.

Comparative Example 1 (Preparation of adhesive) 88 parts of butyl acrylate, 12 parts of acrylamide, azobisisobutyronitrile 0. 6 parts at around 60 ° C. while stirring 3 parts and 250 parts of ethyl acetate.
Reaction was carried out for a time to obtain an acrylic polymer solution having a weight average molecular weight of 1.35 million. An adhesive solution was prepared by adding 0.5 part of Coronate L manufactured by Nippon Polyurethane Company, which is an isocyanate-based polyfunctional compound, to 100 parts of the polymer solid content, to the acrylic polymer solution.

(Preparation of adhesive optical film) Thickness 80 μ
The polyvinyl alcohol film of m was stretched 5 times in an aqueous iodine solution and then dried, and a triacetyl cellulose film was adhered to both sides via an adhesive to obtain a polarizing film. The pressure-sensitive adhesive solution prepared as described above was applied onto a release paper having a thickness of 35 μm so that the thickness after drying would be 18 μm, and this was laminated on the above polarizing film to obtain an adhesive polarizing film.

Comparative Example 2 (Preparation of pressure-sensitive adhesive) 94 parts of butyl acrylate, 6 parts of acrylic acid, 00.3 parts of azobisisobutyronitrile and 200 parts of ethyl acetate were reacted with stirring at 60 ° C. for 6 hours. An acrylic polymer solution having a weight average molecular weight of 1.35 million was obtained. To the acrylic polymer solution, 1 part of isocyanate polyfunctional compound Coronate L manufactured by Nippon Polyurethane Company was added to 100 parts of the polymer solid content to prepare an adhesive solution.

(Production of adhesive optical film) Thickness 80 μ
The polyvinyl alcohol film of m was stretched 5 times in an aqueous iodine solution and then dried, and a triacetyl cellulose film was adhered to both sides via an adhesive to obtain a polarizing film. On the surface of this polarizing film, polymenthine NK3 manufactured by Nippon Shokubai Kagaku Co., Ltd.
80 was applied and dried so that the thickness after drying was 0.1 μm, and a polarizing film with an anchor layer was obtained. The pressure-sensitive adhesive solution prepared as described above was applied onto a release paper having a thickness of 35 μm so that the thickness after drying would be 18 μm, and this was laminated on the anchor layer surface of the polarizing film with an anchor layer prepared as described above for adhesion. A type polarizing film was obtained.

The adhesive polarizing films obtained in the above Examples and Comparative Examples were evaluated as follows. The evaluation results are shown in Table 1.

[Evaluation] (Adhesive Remaining) 50 pieces of the pressure-sensitive adhesive type polarizing film produced as described above were cut into a size of 50 mm × 1500 mm, laminated on Corning non-alkali glass plate # 1737, and 50 ° C. × 5 MPa It was left for 15 minutes in the atmosphere. Next, attach the adhesive polarizing film to the 180 ° direction for 30
Each was peeled from the glass at a speed of 0 mm / min. After that, the number of samples (adhered number) of the adhesives adhered on the glass was visually confirmed.

(Adhesive chipping) The adhesive type polarizing film produced as described above was cut into a size of 25 mm × 150 mm.
The pieces were cut, and these were stacked to form a bundle of polarizing plates. Nitto Denko Co., Ltd. No. The 29 adhesive tapes were bonded together at a pressure of 49 N / 25 mm, and then the adhesive tape was peeled off in the 90 ° direction at a peeling speed of 10 m / min. This peeling operation was repeated 10 times. After that, visually check the edge of each adhesive polarizing film, width 1mm
As described above, the number of adhesive-type polarizing films in which a pressure-sensitive adhesive chipping occurred at a depth of 0.3 mm or more (the number of chipped chips) was confirmed.

(Adhesiveness between Adhesive Layer and Polarizing Film Substrate)
After being cut into a size of m × 150 mm, the pressure-sensitive adhesive layer surface and the 50 μm-thick polyethylene terephthalate film surface are attached so that the vapor deposition surface of the vapor deposition film obtained by vapor deposition of indium-tin oxide is in contact with the surface of the polyethylene terephthalate film, and then 20 minutes or more ,
It was left in an environment of 23 ° C./60% RH. After that, peel off the end of the polyethylene terephthalate film by hand,
After confirming that the adhesive has adhered to the polyethylene terephthalate film side, the stress (N / N) when peeled at a rate of 300 mm / min in 180 ° direction using a tensile tester AG-1 manufactured by Shimadzu Corporation 25 mm) is measured (25
℃).

[0083]

[Table 1]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an adhesive optical film of the present invention.

[Explanation of symbols]

1 Optical film 2 anchor layer 3 Adhesive layer 4 Release sheet

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09J 133/14 C09J 133/14 G02B 5/30 G02B 5/30 (72) Inventor Shigeo Kobayashi 1 Shimohozumi, Ibaraki City, Osaka Prefecture Nicto 1-2 Nitto Denko Co., Ltd. (72) Inventor Akiko Ogasawara 1-2-2 Shimohozumi, Ibaraki City, Osaka Prefecture F-term in Nitto Denko KK (reference) 2H049 BA02 BA06 BB23 BB28 BB33 BB51 BC14 4F100 AJ06 AK01A AK21 AK25B AK25J AK41C AK51B AL01 BA03 BA05 BA10A BA10B EJ65C GB41 JK06B JL01 JL06 JL13B JN01A JN10 YY00B 4J004 AA10 AB01 CA04 CB03 CC02 CD08 CD10 CE01 DB02 DB04 FA01 4J040 DF041 DF051 GA05 GA07 GA11 GA13 GA14 GA22 HD41 HD43 JB09 KA16 LA01 LA06 MA05 MA10 MB03 NA17 PA42

Claims (6)

[Claims] 1. A pressure-sensitive adhesive optical film comprising a pressure-sensitive adhesive layer laminated on one surface of an optical film for bonding the optical film to a glass substrate of a liquid crystal panel, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive. A pressure-sensitive adhesive optical film, wherein the pressure-sensitive adhesive layer is formed of an agent, and the pressure-sensitive adhesive layer is laminated via an anchor layer formed of a polyester resin. 2. The pressure-sensitive adhesive optical film according to claim 1, wherein the polyester resin has polyester as a main skeleton and has a side chain having a hydroxyl group. 3. The pressure-sensitive adhesive optical film according to claim 1, wherein the acrylic pressure-sensitive adhesive contains, as a base polymer, an acrylic polymer containing a monomer having an N element as a monomer unit. 4. The acrylic pressure-sensitive adhesive contains an isocyanate-based polyfunctional compound.
3. The pressure-sensitive adhesive optical film according to any one of 3 above. 5. The pressure-sensitive adhesive layer surface of the pressure-sensitive adhesive type optical film and the vapor deposition surface of the vapor deposition film obtained by vapor-depositing indium-tin oxide on the polyethylene terephthalate film are bonded together, and then the polyethylene terephthalate film is rotated at 180 °.
The pressure-sensitive adhesive optical film according to any one of claims 1 to 4, wherein a stress at 25 ° C when peeled in a direction of 300 mm / min is 13 N / 25 mm or more. 6. A liquid crystal display device using the pressure-sensitive adhesive optical film according to claim 1.